Method of treating cylinders



E. A` SEARLES.

METHOD 0F TREATING CYLINDERS.

APPLlcATxoN FILED lvl/m17, 1920.

lj, wanted Feb. 15,19%

EDWIN A. SEARIES, 0F DETROIT, MICHIGAN.

METHOD 0F TREATING CYLINDERS.

Specification of Letters Patent.

Patented net. i5, rear.

Application mea March 17, 1920. seria1 No. 366,600.

To all whom t may concern.'

Be it known that I, EDWIN A. SEARLES, a citizen of the United States, residing at Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Methods of Treating Cylinders; and I hereby declare that the following is a full, clear, and exact descrlpvtion thereof, reference being had to theaccompanying drawings, .which forni part of this specification.

This invention relates to the manufacture of hollow cast metal bodies, and in particular to the manufacture of cylinders for explosive engines; and it resides in a novel method of internally heating such bodies prior to the final finishing thereof, whereby the cylinders are prevented from becoming warped or distorted when later subjected to the heat developed in actual use thereof.

It is Well known that cast metal bodies are subject to molecular or structural changes due to unequal stresses or strains set up in the metal during the cooling thereof; and it has been found that cast metal bodies', 'such as cylinders for engines, are liable to warp and become distorted when subjected to actual working condi tions; and frequently the distortion is So great as to serlously impair the efliciency and utility of the engine.

In the manufacture of cylinders' for multiple cylinder explosive enginesit hasbeen found that when such cylinders are made in a single casting and finished absolutely true, so that the engine works perfectly when first set up, after short use of the engine the cylinders will frequently warp to such an extent as to necessitate reboring the cylinders and refitting the pistons, and this is difficult and expensive because of the extreme hardness of the inner walls after such use, and such reboring also necessitates refitting the pistons. Usually in multiple-` cylinder engine castings the distortion has the effect of making the cylinder out of round or oval thereby permitting gases to leak past the pistons, and reducing the utility and efiiciency of the engine; and it is very expensive and difficult to remedy the defects. Such a multiple cylinder casty to actual use.

lng, owing to the varying thickness of different portions thereof, cools unequally; and this produces unequal stresses or strains 1n the Walls of the Casting apt to result in warping of the walls'of the cylinder, as above stated, when the same are subjected Various attempts have been made to overcome and prevent this trouble, such as allowing the casting to season be- .fore being used; annealing the entire casting before finishing it; subjecting the casting to magnetic stresses; and various other methods of treatment have been tried with yarying success, but these have either been ineffective, or too expensive on account of the time or labor involved.

My invention aims to overcome all the objections-and to enable the multiple cylinder castings to be rapidly manufactured, and when 1completed be practically free from danger of warping under actual working Conditions. I aim to relieve the stresses or strain of the inner walls of the cylinders lfinish, boring of the cylinders, and not tak- Without changing the parallel planed surfaces .that will be machined prior to the heat treatment, thereby necessitating only the ing a finish cut over the planed surfaces of the cylinder block. The variations in the design of the cylinders would probably require variations in thedegrees of heat, some designs requiring more heat than others. Too high heat would be detrimental, as it would distort the planed surfaces of the cylinder block necessitating re-milling or planing the straight surfaces or top and bottom of block. I simultaneously heat the entire interior walls of the cylinders to a uniform degree of heat sufficient to enable the metal to set and relieve all of the strains or stresses in the casting that would unless eliminated tend to distort the cylinder when heated by the confined exploded gases evolved in the operation of the engine.

This novel method of treatment greatly reduces and practically obviates distortion or warping of the cylinders during subsequent actual use of the cylinders in the engine.

I will explain the invention with reference to the accompanying drawings to enable others to understand and use the same;

and summarize in the claims the essentials of the invention for which protection is desired.

In the drawings:

Figure 1 is'fa perspective view of a conventional form of multiple-cylinder explosive engine casting.

Fig. 2 is a longitudinal section thereof indicating electrical means for heating the interior walls of the cylinders.

Explosive engine cylinders are customarily cast, and ordinarilya multiple of cylinders are formedin the same casting. In the example shownlin Fig. l, three cylinders a, b, c, are formed within a casting having a base 2, as usual, these parts being all formed integral and of approximately the shape shown, the cylinders a, b, c, being roughly formed'in the casting operation by proper cores.

p In carrying out my invention, after the cylinders are cast, as in Fig. 1, I preferably externally dress the casting 1 and base 2, and rough cut the cylinders internally. I then simultaneously locally heat all of the inner walls of the cylinder or cylinders to a temperature preferably higher than the heat to which such cylinder Ior cylinders will be subjected in actual use, that is preferably to a temperature higher than the temperature of the burning exploding gases in such cyliinders. A temperature of from about 800 F. to 12500 F. has been found effective in i the treatment of motor cylinder castings.

fIhis heating maIy be accomplished by any su1table means. prefer to use electrical heaters whereby the entire interior walls of the cylinder or cylinders can be practically simultaneously and uniformly heated. This heating I continue for about twenty minutes to insure that the interior Walls of the cylinders shall be properly and uniformly heated.

After such heating the cylinders are allowed to cool, and then are finished by proper machining as usual.

I do not aim to harden or temper the cylinders but merely to heat all the inner walls thereof substantially simultaneously to a temperature sufficiently high to relieve the stresses and strains in the metal, preparatory to finally finishing or machining the cylinders; thereby obviating the inherent stresses or strains in the metal ofthe casting which would tend to .distort the cylinder or cylinders ,when heated by the hot gases of combusti-on in subsequent actual service.

I have found thatby treating the interior cylinder walls in this novel manner the inherent stresses or strains in the metal of the walls of the cylinder or cylinders are released or equalized.

This method of treating the cylinders greatly facilitates the operation of finally finishing the cylinders and insures the absolute individual uniformity of the cylinders, and their accurate alinement, and parallelism in the finished product, as the finishing cuts are made after the distorting stresses are removed.

I do not use heat for the purpose of hardening or tempering the cylinder walls but merely to relieve the inherent stresses and suitable metal, adapted to be heated by thel passage of an electrical current, and which may be connected with a suitable source of electricity, as indicated in Fig. 2, such resistance coils being roperly insulated from theA metal walls oft e cylinder'.

Each heater 3 may be provided with a .top flange 3a by which it is supported on the upper end of the cylinder when inserted therein, as in Fig. 2. Each cylinder may have its own heater; and the heaters may be connected in series as indicated in Fig. 2; and ma be energized either by direct or alternatmg electric currents.

What I claim is:

1. T'he herein described method of treating hollow metal bodies such as the cylinders of explosive engines to eliminate or equalize the inherent stresses and strains in the casting which would tend to later distort the casting when in actual use; consisting in locally heating the inner walls of the casting sufficiently to relieve all stresses or strains in the casting which would tend to A convenient form of electriv distort the'casting when heated in subsequent use, substantially as described.

2. The herein described method of treating hollow cast metal bodies such Vas the cylinders of explosive engines to eliminate or equalize the inherent stresses and strains in the casting which would tend to later distort the casting' when in actual use; consisting in locally applying heat to the inner walls of the casting to raise same to a temperature approximately that to which the body would be subjected in actual use, substantially as described, 1

3. The herein described method of treating hollow metal bodies such as the cylinders of explosive engines to eliminate or equalize inherent stresses and strains in the casting which would tend to later distort the cylinders when in actual use; consisting in uniforinly heating the inner Walls of the cylinder to relieve all stresses or strains in the casting which would tend to make the cylinders out of round when heated in subsequent use; and thereafter finishing the interior Walls of the cylinder, substantially as described.

4. The herein described method of treating cast metal bodies such as the cylinders i of explosive engines to eliminate or equalize the inherent stresses and strains in the casting which would tend to later distort the cylinder When in actual use; consisting in locally applying heat to the inner Walls of the cylinder to raise same to a temperature approximating that to which the cylinder would be subjected in actual use, :and thereafter iinishing the interior Walls of the cylinder, substantially as described.

5. The herein described method of treating cast metal cylinders for explosive eny gines; consisting in locally heating the inner walls of the cylinder to a temperature approximating thev normal temperature to which the cylinders would be subjected when in actual use, thereby relieving the stresses or strains in the casting Which would other- Wise tend to distort the cylinders, When heated in subsequent use7 substantially as described.

6. The herein described method'of treating cast metal cylinders; consisting in first casting the cylinder, then heating all the inner Walls of the cylinder by suitable heating devices to a temperature approximating the normal temperature of that to which the cylinder would be subjected When in actual use to relieve all stresses or strains in the casting which Would otherwise tend to distort the cylinder when heated in subsequent use: and thereafter cooling the casting and finishing the bore of the cylinder, substantially as set forth.

In testimony that I claim the foregoing as my own,` l aix my signature.

VEUWIN A. SEARLES. 

